ABSTRACT Heart failure (HF) is the leading cause of hospitalization among adults over 65 years of age in the United States. In 2014, more than 5.1 million people in the United States were living with a diagnosis of HF, and as many as one in nine deaths each year can be attributed to complications stemming from this disease. The neurohormonal imbalance associated with heart failure leads to fluid retention, resulting in an increase in intracardiac filling pressures, passive elevation of pulmonary venous and arterial pressures, and pulmonary fluid accumulation. Detecting hemodynamic congestion prior to symptom onset allows for early intervention and prevention of hospitalizations. Various parameters have been utilized for patient self-monitoring of cardiac function, including weight tracking, but have shown limited efficacy in reducing hospitalizations. Changes in both pulmonary artery pressure (PAP) and stroke volume (SV) are capable of detecting changes in cardiac function relatively early, but typically require specialized equipment that is not feasible for at-home use. Recent evidence has shown that directly monitoring of PAP via an implantable sensor (CardioMEMS) can provide clinicians with a remote monitoring tool to determine when medication adjustments were needed to prevent decompensation, and reduced 30-day readmissions by 37%. However, the cost (~$25k) and invasive nature of this device severely restricts its clinical adoption rate. TheraNova has developed a non-invasive, handheld respiratory monitor (Cardiospire) that is capable of directly monitoring cardiac function in a remote setting. The device detects minor variations in naturally expired airflow pressure known as cardiogenic oscillations (COS), which correspond with the cardiac cycle. Decreasing SV and increasing PAP both act to diminish the amplitude of COS with worsening HF. In pilot in vivo studies, we have demonstrated that COS is a direct indicator of cardiac function through its direct correlation with SV and inverse proportionality to PAP. The overall objective of this project is to measure COS using the Cardiospire device in stabilized and decompensated HF patients. In Aim 1, we will validate the ability of the device to perform repeatable measurements of COS in HF patients. In Aim 2, we will validate the ability of the device to detect clinically significant changes in cardiac function in HF patients using COS in an observational clinical study. The results of these two aims will provide essential information about device function that we will use during Phase II in a larger clinical study to evaluate Cardiospire as an at-home monitoring system. Ultimately, Cardiospire will allow physicians to remotely monitor their patients? fluid status and make adjustments to their medications in order to prevent hospitalizations. This type of non-invasive home monitoring could potentially prevent many unnecessary hospitalizations for acute decompensation.